Timothy Rustige, 65, was on trial accused of causing Dame Elish Angiolini to suffer fear and alarm by subjecting her to a campaign of harassment.
Dame Elish QC said she feared for her family's safety after a group of conspiracy theorists targeted her between February 27 and March 22, 2012.
The former lord advocate said she had been subjected to threatening emails and blog posts saying she was responsible for the cover-up of a paedophile ring in Aberdeen.
Yesterday at Aberdeen Sheriff Court, after a two-day trial, Sheriff Principal Derek Pyle took just a few minutes to declare Rustige guilty. Sentence was deferred for reports until next month and Rustige, who had denied the allegations, was released on bail.
The court heard how highly defamatory emails had been sent to Oxford, Aberdeen and Strathclyde universities claiming Dame Elish was a "satanic woman". During his evidence the former mechanical engineer blamed everyone from his wife, his son - also called Timothy Rustige - to members of a political activist group called Prisoners of Conscience for writing the material.
The emails, which were read out in court, claimed a variety of establishment figures had been sexually abusing a young girl.
They claimed Dame Elish had been aware of the paedophile ring and had covered it up. Other emails claimed she had been directly involved in the murder of the abused girl's uncle, who was found to have committed suicide.
The court heard earlier that Dame Elish said the allegations were hurtful and completely false and merely "the rantings of crazy people and conspiracy theorists".
Giving evidence, Dame Elish said that she had employed extra security for herself and her family as a result of the messages. She said she also feared for her safety when out in public.
Rustige claimed posts on Facebook defaming Dame Elish were actually written by another member of the Prisoners of Conscience. When asked what the organisation did, Rustige replied: "We did work with the Palestinians, we worked with Edward Snowden, Bradley Manning, Julian Assange."
The court heard yesterday that Police Scotland computer analysts linked Rustige's desktop computer to various online Hotmail accounts which sent some of the emails.
Defence agent David Moggach said: "You are accused of being involved in a campaign of harassment - were you involved?" Rustige replied: "No. It was the Prisoners of Conscience."
Fiscal Depute Christopher Macintosh said: "The truth is it's a misnomer you are part of Prisoners of Conscience as you have not shown to have a conscience.
"You have pointed the finger at your son, your wife - anyone to get yourself out of trouble. If this wasn't so serious it would be laughable. This is not the protection of your free speech. This is the protection of an individual from horrible defamatory comments."
Sheriff Pyle said he would keep all options open - including a possible jail sentence.